1. Field of the Invention
This invention relates to a photographic light-sensitive material, and more particularly, to a photographic light-sensitive material which is rendered antistatic.
2. Description of the Prior Art
In the preparation of photographic light-sensitive materials or in the use thereof, static electric charges are generated in the photographic light-sensitive materials and the charges accumulate, which cause various undesirable phenomena. This accumulation of static charge results from the contact of a film with a roller, the friction of a film with another material in a camera, the contact of the emulsion surface of a roll film with the back surface at the opposite side of the support of the film, and the like, and it is subsequently discharged. The photographic light-sensitive materials are sensitized before image-wise exposure by this static phenomenon and produce irregular static marks after development. In general, as the sensitivity of the photographic emulsion increases, the emulsion becomes more susceptible to the discharge of static charge, thus resulting in an increase in static marks.
In order to prevent build-up of static charge in photographic light-sensitive materials, antistatic agents are generally used. Typical examples of antistatic charges are, in particular, electrically conductive surface active agents (e.g., anionic, cationic, nonionic surface active agents, etc.), and polymers (e.g., .alpha.,.beta.-unsaturated carboxylic acid copolymers such as polyacrylic acid or polymethacrylic acid, carboxymethyl cellulose, polycarboxylate salts, polystyrenesulfonate salts, etc.). However, since many of these antistatic agents can be dissolved only in water, these antistatic agents have poor wettability of coated layers as compared with antistatic agents which can be dissolved in organic solvents or both organic solvents and water. In particular, when photographic light-sensitive materials are rolled or stacked as sheets and are allowed to stand at high temperature and high humidity, the layer of an antistatic agent and an emulsion layer come into contact with each other. Therefore, when the photographic light-sensitive materials are separated from each other in this case, undesirable phenomena for photographic light-sensitive materials such as the occurrence of static marks, gloss or development mottle, or a delamination of the emulsion layer occur. Moreover, some surface active agents are transferred to the surface of the emulsion layer or penetrate to the support, so that they do not satisfactorily exhibit the intended antistatic effect.
For the above and other reasons and in view of the advantages in using a binder at the same time, organic solvents are often used in coating an antistatic agent. However, antistatic agents of the anionic type (particularly polymers) can not be dissolved in organic solvents in may cases. Moreover, although cationic surface active agents can be dissolved in organic solvents, it is very difficult to select stable cationic surface active agents since they influence the photographic properties of an emulsion (such as desensitization). From this point of view, copolymers with .alpha.,.beta.-unsaturated carboxylate salts have been proposed as described in U.S. Pat. Nos. 3,446,651 and 3,514,291, British Patent Nos. 1,155,997 and 1,267,732, Japanese Patent Publication Nos. 24158/71 and 24159/71, Japanese Patent Application (OPI) No. 3972/74 and Japanese Patent Publication No. 23827/74. However, solubility of these polymers in organic solvents (such as alcohols, esters, ketones or mixtures thereof), the anti-adhesion properties of these polymers to an emulsion layer, the transparency of a coated layer of these polymers, the stability of these polymers with time, and the like are insufficient, and therefore, the application of these polymers to photographic light-sensitive materials has not yet been put into practice.